EP1906153A2 - Rotary encoder and method for its operation - Google Patents

Abstract

The rotary encoder has an exciter control unit formed such that exciter conductive lines (2.21) are selectively operable in two operating modes, where two exciting currents are producible in the respective operating modes. One exciting current is formed such that an electrical power input of the rotary encoder in one operating mode is smaller than the other operating mode, and the exciting currents induce respective voltages in a detector arrangement, where the voltages are electronically processed for producing angular position information from an evaluation unit. An independent claim is also included for a method for operating a rotary encoder.

Description

The invention relates to a rotary encoder for determining relative angular positions, which operates on an inductive measuring principle, according to claim 1 and a corresponding method for operating such a rotary encoder according to claim 11.

Inductive rotary encoders are used, for example, to determine the angular position of two machine parts which can be rotated relative to one another. In inductive encoders excitation windings and receiver coils are applied approximately in the form of printed conductors on a common printed circuit board, which is firmly connected, for example, with a stator of a rotary encoder. Opposite this printed circuit board there is another board, which is not infrequently designed as a code disk, on which periodically spaced electrically conductive and non-conductive surfaces are applied as a division or division structure, and which is rotatably connected to the rotor of the encoder. When a time-varying electric excitation field is applied to the excitation windings by impressing an exciting current, in the receiver coils during the relative rotation generated between the rotor and stator of the angular position dependent signals. These signals are then further processed in an evaluation.

Frequently, such encoders are used as measuring devices for electric drives, for determining the absolute angular position of corresponding drive shafts. It is particularly important from a safety point of view, that even after turning off the system or in case of power failure at least the turns made in this state are counted.

In the DE 197 51 853 A1 The applicant describes a structure for an inductive rotary encoder in which the exciter and receiver coils are arranged in a multilayer printed circuit board structure.

In order for such a rotary encoder to be able to count at least the number and direction of rotation of the recirculated revolutions even if there is no mains voltage supply, two magnets were previously provided on the rotor and two magnetic sensors on a stator printed circuit board which generate counting signals. The magnetic sensors were supplied in this operating state by a backup battery.

The invention has for its object to provide an inductive rotary encoder, which is simple in construction and can be generated by the even with reduced supply of electrical energy position signals. Furthermore, the invention has the object to provide a method which allows the use of a simply constructed rotary encoder, which generates position signals even with a reduced supply of electrical energy.

This object is achieved by the features of claim 1 and of claim 11.

According to the invention, the rotary encoder comprises inter alia a shaft and a carrier body on which an excitation winding and a detector arrangement are arranged. Through the excitation winding, an excitation current can be conducted to generate an electromagnetic field, and the detector arrangement is used to scan the electromagnetic field influenced by a code carrier Field suitable. Furthermore, the rotary encoder comprises a pathogen control element and an evaluation element. The shaft is rotatable relative to the carrier body, being fixed in rotation on the shaft for detecting its angular position of the code carrier. The exciter control element is designed such that it can be operated by the excitation winding selectively in two different operating modes in such a way that in the first operating mode, a first excitation current and in the second operating mode, a second excitation current can be generated, wherein the second excitation current is configured such that the electrical power consumption of the rotary encoder in the second operating mode is smaller than in the first operating mode. The respective exciter current induces voltages in the detector arrangement which can be processed electronically by the evaluation element in order to generate angular position information.

The exciter control element is in particular designed such that in the first operating mode, a first excitation current and in the second operating mode, a second excitation current can be generated, wherein the effective value of the second excitation current is smaller than that of the first excitation current. The effective value of the respective exciting current is to be understood as the value by which the same energy is dissipated in the same exciting winding as an equal DC current in the same time, whereby the time must of course exceed a certain minimum duration, for example one second. The rotary encoder can be operated in the second operating mode with less electrical energy than in the first operating mode.

In a further embodiment of the invention, the angular position information generated in the second operating mode has a coarser resolution than the angular position information generated in the first operating mode. This means that the accuracy of the detection of the angular position in the second operating mode is reduced compared to that in the first operating mode.

Advantageously, the detector arrangement comprises a first detector winding and a second detector winding, wherein the first detector winding within one revolution relative to the carrier body delivers a different number of signal periods than the second detector winding. It is It is advantageous if the first detector winding supplies an odd number of signal periods, in particular if the first detector winding supplies only one signal period during one revolution.

Furthermore, it is advantageous if the first detector winding supplies a smaller number of signal periods within one revolution relative to the carrier body than the second detector coil.

In a further embodiment of the invention, the rotary encoder is configured so that only the voltage induced in the first detector winding voltage is detectable for generating angular position information in the second operating mode, while in the first mode of operation additionally the induced voltages of the second detector winding are each electronically processed by the evaluation. Accordingly, the voltage induced in the first detector winding is electronically processed by the evaluation element for generating angular position information in the second operating mode and at the same time disregards the voltage induced in the second detector winding for the electronic processing, that is to say that the voltage induced in the second detector winding is then subtracted from the voltage electronic processing is disconnected or separated. Thus, the second detector winding in the second operating mode has no function for the generation of angular position information. In contrast, in the first operating mode, both the voltages induced in the first detector winding and in the second detector winding are electronically processed for generating angular position information.

Advantageously, the exciter control element and the evaluation element can be integrated in an ASIC module.

In a further embodiment of the invention, the exciter control element can be designed such that the second excitation current can be generated as a pulsed current. In particular, the second excitation current may comprise current pauses. Current pauses are time ranges in which the excitation current practically goes back to zero.

The rotary encoder itself can have a battery for the power supply of the rotary encoder in the second operating mode.

Furthermore, the invention relates to a method for operating such a rotary encoder with the steps: selecting a first or second operating mode; Generating an excitation current in the exciter winding with the aid of the exciter control element, wherein in the first operating mode, a first excitation current and in the second operating mode, a second excitation current are generated, wherein the second excitation current is configured such that the electrical power consumption of the encoder is smaller in the second operating mode than in the first Operation mode; Detecting the voltage induced by the respective exciting current in the detector arrangement; electronic processing of the induced voltage to generate angular position information.

In particular, the excitation currents are generated in such a way that the rms value of the second excitation current is smaller than that of the first excitation current.

Advantageously, the first or the second operating mode is selected as a function of the voltage applied to the rotary encoder. For example, the height of the actual applied voltage level can be used as criteria for this, or, for example, the current voltage profile in each case (eg DC voltage - AC voltage).

The exciter current in the second operating mode is advantageously designed so that the time interval between adjacent current maxima at least 100 times, advantageously at least 1000 times or at least 2500 times greater than the time interval of adjacent peak current in the first operating mode. The exciter current reaches a maximum current, if this has its maximum amplitude. The term maximum current may be understood in terms of amount, so that in this case there is a maximum current even with a magnitude-maximum negative current. If the excitation current has no pronounced singular maximum, z. B. if rectangular pulses are present in which the maximum current over a remains constant for a certain time, then the temporal center of the maximum current is to be understood for the above-mentioned time intervals, z. B. the time which lies between the edges of a rectangular pulses.

In a further embodiment of the invention, the detector arrangement comprises a first detector winding and a second detector winding, wherein the first detector winding within a revolution relative to the carrier body provides a different number of signal periods relative to the second detector winding, and detected in the second operating mode, only the voltage induced in the first detector winding voltage and is processed to generate angular position information. Furthermore, in the first operating mode, the voltage induced in the second detector winding can then also be detected and processed to generate angular position information.

Advantageous embodiments of the invention will remove the dependent claims.

Further details and advantages of the inductive rotary encoder according to the invention, as well as the method for its operation will become apparent from the following description of an embodiment with reference to the accompanying figures.

Figur 1

eine Draufsicht auf eine Codescheibe,

Figur 2

eine Draufsicht auf eine Abtastleiterplatte,

Figur 3a

einen Signalverlauf des Erregerstroms in den Erregerwindungen in einem ersten Betriebsmodus,

Figur 3b

einen Signalverlauf der induzierten Spannung in Detektorwindungen im ersten Betriebsmodus,

Figur 4a

einen Signalverlauf des Erregerstroms in den Erregerwindungen in einem zweiten Betriebsmodus,

Figur 4b

einen Signalverlauf der induzierten Spannung in einer Detektorwindung im zweiten Betriebsmodus (0° Phase)

Figur 4c

einen signalverlauf der induzierten Spannung in einer Detektorwindung im zweiten Betriebsmodus (90° Phase)

Figur 5

ein schematisches Schaltbild,

Figur 6

eine Schnittdarstellung eines Drehgebers.

It show the

FIG. 1

a top view of a code disk,

FIG. 2

a plan view of a Abtastleiterplatte,

FIG. 3a

a waveform of the excitation current in the excitation windings in a first operating mode,

FIG. 3b

a waveform of the induced voltage in detector windings in the first mode of operation,

FIG. 4a

a waveform of the excitation current in the excitation windings in a second operating mode,

FIG. 4b

a waveform of the induced voltage in a detector winding in the second operating mode (0 ° phase)

Figure 4c

a signal curve of the induced voltage in a detector winding in the second operating mode (90 ° phase)

FIG. 5

a schematic diagram,

FIG. 6

a sectional view of a rotary encoder.

In Figures 1, 2 and 6, the basic structure of a rotary encoder according to the invention is shown. According to FIG. 6, the rotary encoder has a rotor 1 and a stator 2. In the illustrated embodiment, the rotor 1 comprises a shaft 1.1, which can be rotatably mounted, for example, on a motor shaft to be measured. At a shoulder of the shaft 1.1 is for detecting their angular position of the code carrier in the form of a code disk 1.2 with - not shown in the figure 6 - graduation tracks 1.21, 1.22 fixed against rotation.

The stator 2 comprises a housing 2.1, to which a ring-shaped scanning printed circuit board 2.2 is attached as the carrier body. Among other things, a connector 2.3 is mounted on the Abtastleiterplatte 2.2, through which signals and electrical power can be transmitted. The rotor 1 and the stator 2, or the shaft 1.1 and the housing 2.1 are rotatable relative to each other about a rotation axis R.

In the figure 1, the code disk 1.2 is shown in a plan view. The code disk 1.2 consists of a substrate, which is made in the illustrated embodiment of epoxy resin and are arranged on the two graduation tracks 1.21, 1.22. The graduation tracks 1.21, 1.22 are ring-shaped and arranged with respect to the rotation axis R concentric with different diameters on the substrate. The two graduation tracks 1.21, 1.22 each consist of a periodic sequence of alternately arranged electrically conductive graduation regions 1.211, 1.221 and nonconductive divisions 1.212, 1.222. As a material for the electrically conductive portions 1.211, 1.221 copper was applied to the substrate in the example shown. In the nonconductive graduation regions 1.212, 1.222, however, the substrate 2.3 was not coated.

The inner dividing track 1.21 consists in the illustrated embodiment of a first semi-annular dividing area 1.211 with electrically conductive material, here copper, and a second semi-annular dividing area 1.212, in which no conductive material is arranged.

Radially adjacent to the first graduation track 1.21, the second graduation track 1.22 lies on the substrate, the graduation track 1.22 also consisting of a multiplicity of electrically conductive graduation areas 1.221 and nonconductive graduation areas 1.222 arranged therebetween. The different division regions 1.221, 1.222 are materially formed here as well as the division regions 1.211, 1.212 of the first division track 1.21. Overall, the second graduation track 1.22 in the illustrated embodiment comprises sixteen periodically arranged, electrically conductive graduation areas 1.221 and correspondingly sixteen non-conductive graduation areas 1.222 arranged therebetween.

The scanning printed circuit board 2.2, shown in FIG. 2 and intended for scanning the code disk 1.2, serves as a carrier body, inter alia, for a detector arrangement, which here consists of different receiver coils 2.22. These receiver coils 2.22 have receiver traces 2.221 as first detector windings in an inner receiver track and further receiver traces 2.222 as second detector windings in an outer receiver trace. Associated pairs of the receiver tracks 2.221, 2.222 of a respective receiver track are offset relative to each other, so that they can provide 90 ° out of phase signals.

In addition, exciter tracks 2.21 are provided as excitation windings on the scanning board 2.2, which are applied to an inner, a middle and an outer register track. The scanning board 2.2 itself has a central bore and is designed as a printed circuit board having a plurality of layers.

In the assembled state, the code disk 1.2 and the Abtastleiterplatte 2.2 are opposite, so that the axis R passes through the centers of both elements and in a relative rotation between code disk 1.2 and scanning 2.2 in the Abtastleiterplatte 2.2 a dependent of the respective angular position signal is generated by induction effects ,

The prerequisite for the formation of corresponding signals is that the exciter printed conductors 2.21 generate a time-varying electromagnetic excitation field in the area of the scanning tracks or in the area of the graduation tracks 1.21 and 1.22 scanned therewith. In the illustrated embodiment, the exciter printed conductors 2.21 are formed as a plurality of planar-parallel current-carrying individual printed conductors. If the exciter printed conductors 2.21 of a printed conductor unit all flow through an excitation current in the same direction, then a tubular or cylindrical electromagnetic field is formed around the respective printed conductor unit. The field lines of the resulting electromagnetic field run in the form of concentric circles around the conductor track units, wherein the direction of the field lines in a known manner depends on the current direction in the conductor track units. The current direction of the conductor track units directly adjoining a common scanning track or the corresponding interconnection of these track track units is to be chosen opposite, so that the field lines in the area of the scanning tracks are each oriented identically.

FIG. 5 schematically shows a circuit by means of which the mode of operation of the rotary encoder is to be explained. The rotary encoder is connected via the connector 2.3 (FIG. 6) and a cable to an external DC voltage source 3. In normal operation, the rotary encoder is powered by the external DC voltage source 3. In the illustrated embodiment, the voltage U _{C of} the DC voltage source 3 is five volts.

In the event that, for some reason, the DC voltage source 3 is not available, the encoder is temporarily powered by a battery 4 with electrical energy, in which case the output voltage from the battery 4 may be for example three volts. The battery 4 can either be housed directly in the rotary encoder, for example on the Abtastleiterplatte 2.2, or externally, so that also supplied by the battery 4 electrical energy via the cable and the connector 2.3 can get into the encoder.

On the Abtastleiterplatte 2.2 ASIC module is mounted 2.23, which operates as a excitation control element, under the control of the excitation current I _I , I _{II is} generated. How this excitation current I _I , I _{II is} configured depends on whether the rotary encoder is supplied by the DC voltage source 3 or by the battery 4. Accordingly, the ASIC module 2.23 is connected to the supply line, so that at an input of the ASIC module 2.23 the currently present voltage U _C or U _B is present. If it is ascertained by the ASIC module 2.23 that the voltage U _C is present at the rotary encoder, ie if the rotary encoder is in normal operation, the ASIC module 2.23 drives the excitation conductor tracks 2.21 in a first operating mode with a first excitation current I _I. In the first operating mode, the excitation current I _I in the illustrated embodiment, a frequency of one MHz, so that the time interval τ _I between adjacent peak current in the first mode of operation is 1 microseconds. Accordingly, the capacitors 2.24 and the exciter printed conductors 2.21, which form an electrical resonant circuit, dimensioned. The ASIC module 2.23 is configured so that the resonant circuit at each zero crossing of the excitation current I _I, a minimum current pulse is supplied, which is so dimensioned that just the losses are compensated in the resonant circuit. Accordingly, the excitation current I _I in the first operating mode, as shown in Figure 3a, be referred to as a periodic excitation current I _I , wherein in the illustrated embodiment, the maximum amplitude has a value of +70 mA and -70 mA.

As a result of the first excitation current I _I , 2.222 voltages U _{I are} induced in the receiver coils 2.22, that is to say in the receiver conductor tracks 2.221, 2.222 as a function of the angular position of the code disk 1.2. Receiver traces 2.221 include two traces that provide 90 ° offset voltage signals. Within a revolution relative to the carrier body, ie at a rotation angle of 2π (360 °), the receiver tracks 2.221 each provide a single signal period in the scanning of the division track 1.21. As a result of the staggered arrangement of the printed conductors in the region of the receiver printed conductors 2.221, two induced voltages U _I , whose envelopes have a phase offset of 90 ° relative to one another, arise during operation of the rotary encoder.

From the scanning of the graduation track 1.21 so results in a relatively coarse, absolute position information within a revolution of the code disk 1.2 about the axis of rotation R. These signals provide a unique absolute position signal within a revolution of a shaft 1.1. By evaluating the signals offset by 90 °, a directional detection of the rotational movement is also ensured.

The other receiver printed conductors 2.222 on the second, outer scanning track are used for scanning the second graduation track 1.22. A relative offset is likewise provided between the two receiver printed conductors 1.7, 1.8, so that on the output side when scanning the second graduation trace 1.22 two signals are produced, between whose envelopes a 90 ° phase offset exists.

The outer receiver circuit traces 2.222 each have sixteen, that is 2 ^4, turns, so that a comparatively high-resolution incremental signal during the relative movement of the code disk can be generated with respect to the scanning printed circuit board 1.2 2.2 with the outer receiver circuit traces 2,222. Within one revolution relative to the carrier body, ie at a rotation angle of 2π (360 °), the receiver tracks 2.222 each provide sixteen signal periods in the scanning of the division track 1.22.

In conjunction with the coarse absolute position determination over the first graduation track 1.21, a high-resolution absolute rotational angle determination is possible via such an arrangement.

FIG. 3b shows a time profile of the voltages U _I in one of the receiver printed conductors 2.221, as well as the two enveloping sinusoidal curves. In combination with the induced voltages U _{I of} the remaining receiver printed conductors 2.221, 2.222, corresponding sinusoidal signals can be formed by a demodulation method, by means of which the exact angular position of the shaft 1.1 can be determined. The induced voltages U _I from the ASIC module 2.23, which now also serves as an evaluation element, are processed electronically in such a way that a corresponding angular position information for the shaft 1.1 is generated. Accordingly, therefore, the exciter control element and the evaluation element are integrated in a single ASIC module.

As a result of the high frequency of the excitation current I _I , it is possible that virtually any time the current angular position information can be retrieved from the encoder. In addition, counting of whole revolutions is possible.

If, for example due to a power failure, the DC voltage source 3 is not available, the voltage U _{B of} the battery 4 is applied to the encoder. This recognizes the ASIC module 2.23 and then selects the second mode of operation, so that the ASIC module 2.23 the exciter tracks 2.21 now drives the much power-saving second mode of operation, the rms value of the second excitation current I _{II is} smaller than that of the first excitation current I _I , In the second operating mode, a pulsed excitation current I _{II is} generated, according to FIG. 4a. This means that as a result of the control of the ASIC module 2.23 current pulses having a frequency of, for example, 200 Hz are impressed into the exciter printed conductors 2.21, so that the time interval τ _II between adjacent current maxima in the second operating mode is 0.005 s. Thus, in the second operating mode, the time interval τ _II between adjacent current maxima is 5000 times greater than the time interval τ _{I of} adjacent maximum currents I _I in the first operating mode. Between the pulses lies in the second Operating mode in each case a current pause, in which the value of the excitation current I _II in the second operating mode is virtually equal to zero. Due to the comparatively low frequency and the low pulse time (eg T = 1 μs), as well as a low current amplitude (eg maximum amplitude = 20 mA), the current requirement of the rotary encoder becomes significant in the second operating mode compared to that of the first operating mode reduced, or is the electrical power consumption, so the need of the encoder to electrical energy with respect to an operating second, in the second mode of operation substantially smaller than in the first mode of operation. In the second operating mode and in the first operating mode, the same excitation conductor tracks 2.21 are traversed by the second exciter current I _II or by the first excitation current I _I.

The pulsed excitation current I _II induced in response to the angular position of the code disk 1.2 in the receiver conductors 2.221 a voltage U _II (response pulse). The receiver tracks 2.221 comprise, as already described, two tracks, which provide in the result 90 ° offset voltage signals. 4b shows, for example, the time profile of the voltage U _II as it is induced in the first of the receiver conductors 2.221 (eg 0 ° phase). The ASIC module 2.23 operating as an evaluation element determines that the voltage U _II (0 °) has exceeded a threshold value U _L. At the same time, it is also found that the voltage U _II (90 °) induced in the second of the receiver conductors 2.221 (eg 90 ° phase) has not reached the threshold value U _L.

These input conditions are processed electronically by the ASIC module 2.23 as an evaluation element in such a way that an angular position information is generated. The angular position information generated in the second operating mode is comparatively coarse or inaccurate. However, it can at least be determined which quadrant the angular position of the shaft 1.1 can be assigned to. This is important, for example, when the motor shaft is moved on uncontrolled by a suspended load. Because then can be at least determined in the second mode of operation as many revolutions of the shaft has covered 1.1 and in which direction. Accordingly, the number of revolutions can be counted even with failed DC voltage source 3, so that the number of revolutions is not lost.

Depending on the position of the code disk 1.2, the induced voltage U _{II can} also fall below the lower threshold value -U _L. Thus, it will be different for each phase whether U _II ≥ U _L , -U _L <U _II <+ U _L or U _II ≦ U _L. Accordingly, a unique quadrant assignment can be made for the position of the shaft 1.1.

Claims (19)

Encoder comprehensive a wave (1.1), - A support body (2.2) on which · At least one excitation winding (2.21), through which an excitation current (I _I , I _II ) can be conducted to generate an electromagnetic field, as well as At least one detector arrangement (2.22) are arranged for scanning the electromagnetic field influenced by a code carrier (1.2), - An exciter control element (2.23) and - An evaluation element (2.23), wherein
the shaft (1.1) is rotatable relative to the carrier body (2.2) and is rotationally fixed to the shaft (1.1) for detecting its angular position of the code carrier (1.2), wherein
the exciter control element (2.23) is designed in such a way that the excitation winding (2.21) can be operated selectively in two different operating modes, in such a way that a first excitation current (I _I ) in the first operating mode and a second excitation current (I _II ) in the second operating mode ), wherein the second excitation current (I _II ) is designed such that the electrical power consumption of the rotary encoder in the second operating mode is smaller than in the first operating mode, and
the respective excitation current (I _I, I _II) in the detector arrangement (2.22) voltages (U _I, U _II) induced which are electronically processed to generate angular position information from the evaluation element (2.23). Rotary encoder according to claim 1, wherein the angular position information generated in the second operating mode has a coarser resolution than the angular position information generated in the first operating mode. A rotary encoder according to claim 1 or 2, wherein the detector arrangement (2.22) comprises a first detector turn (2.221) and a second detector turn (2.222) and the first detector turn (2.221) within one revolution relative to the carrier body (2.2) one opposite the second detector turn (2.221). 2.222) provides different numbers of signal periods. A rotary encoder according to claim 3, wherein the first detector winding (2.221) provides an odd number of signal periods. Rotary encoder according to claim 4, wherein the first detector winding (2.221) within a revolution relative to the carrier body (2.2) delivers a smaller number of signal periods than the second detector winding (2.222). Rotary encoder according to one of claims 3 to 5, wherein the evaluation element (2.23) for generating angular position information in the second operating mode, the voltage (U _II ) induced in the first detector winding (2.222) can be processed electronically and at the same time the voltage (U _II ) induced in the second detector winding (2.222) is ignorable for the electronic processing, and In the first operating mode, both the voltages (U _I ) induced in the first detector winding (2.221) and in the second detector winding (2.222) can be processed electronically. Rotary encoder according to one of the preceding claims, wherein the exciter control element (2.23) and the evaluation element (2.23) are integrated in an ASIC module. Rotary encoder according to one of the preceding claims, wherein the exciter control element (2.23) is designed such that the second excitation current (I _I ) can be generated as a pulsed current. Rotary encoder according to one of the preceding claims, wherein the exciter control element (2.23) is designed such that the second exciter current (I _II ) has current pauses. Rotary encoder according to one of the preceding claims, wherein the rotary encoder has a battery for the power supply of the rotary encoder in the second operating mode. Method for operating a rotary encoder, the a wave (1.1), - A support body (2.2) on which · At least one excitation winding (2.21) through which an excitation current (I _I , I _II ) is passed to generate an electromagnetic field, as well as At least one detector arrangement (2.22) are arranged for scanning the electromagnetic field influenced by a code carrier (1.2), - An exciter control element (2.23) and - An evaluation element (2.23), wherein
the shaft (1.1) is rotatable relative to the carrier body (2.2) and is rotationally fixed to the shaft (1.1) for detecting its angular position of the code carrier (1.2), with the following steps ◆ selecting a first or second operating mode, Generating an excitation current (I _I , I _II ) in the excitation winding (2.21) by means of the excitation control element (2.23), wherein in the first operating mode, a first excitation current (I _I ) and in the second operating mode, a second excitation current (I _II ) are generated, wherein the second excitation current (I _II ) is designed such that the electrical power consumption of the rotary encoder in the second operating mode is smaller than in the first operating mode, ◆ detecting the voltage (U _I U _II ) induced by the excitation current (I _I , I _II ) in the detector arrangement (2.22), ◆ electronic processing of the induced voltage (U _II , U _I ) to generate angular position information. Method according to claim 11, wherein the angular position information generated in the second operating mode has a coarser resolution than the angular position information generated in the first operating mode. Method according to claim 11 or 12, wherein the first or the second operating mode is selected as a function of the voltage applied to the rotary encoder (U _B , U _C ). A method according to any one of claims 11 to 13, wherein the second excitation current (I _II ) is generated as a pulsed current. A method according to any one of claims 11 to 14, wherein the second excitation current (I _II ) comprises current pauses. Method according to one of claims 11 to 15, wherein the second excitation current (I _II ) is designed such that the time interval (τ _II ) between adjacent current maxima is at least 100 times greater than the time interval (τ _I ) of adjacent current maxima of the first Excitation current (I _I ). A method according to claim 16, wherein the second excitation current (I _II ) is designed so that the time interval (τ _II ) between adjacent current maxima is at least 1000 times greater than the time interval (τ _I adjacent maximum current of the first excitation current (I _I ). Method according to one of claims 11 to 17, wherein the detector arrangement (2.22) comprises a first detector turn (2.221) and a second detector turn (2.222) and the first detector turn (2.221) within one revolution relative to the carrier body (2.2) one opposite the second detector turn (2.222) provides different numbers of signal periods, in the second operating mode, the voltage (U _II ) induced in the first detector winding (2.222) is processed electronically and at the same time the voltage (U _II ) induced in the second detector winding (2.222) is disregarded by the electronic processing, and In the first operating mode, both the voltages (U _I ) induced in the first detector winding (2.221) and in the second detector winding (2.222) are processed electronically. Method according to one of claims 11 to 18, wherein the first excitation current (I _I ) has a higher maximum amplitude than the second excitation current (I _II ).

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